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Air pollution decreased, but still causes hundreds of deaths a year in Allegheny County

Smoke rises from U.S. Steel's Clairton Coke Works.
Reid Frazier
The Allegheny Front
U.S. Steel's Clairton Coke Works is the top contributor of PM2.5 air pollution in Allegheny County.

A new report by the Breathe Project finds that residents of Allegheny County are more likely to die from air pollution than people in other parts of the U.S.

The report looked specifically at exposures to fine particulate matter, also called PM2.5, which largely comes from industrial sources. The particles are so tiny, with diameters 2.5 micrometers or smaller, that when people breathe them in, they can get deep into the lungs and the bloodstream.

The latest analysis found that air pollution in Allegheny County improved between 2020 and 2022, and that it had been reduced 28.5% over the preceding decade. Still, an estimated 640-1373 people died each year in the county from PM2.5 from 2020 to 2022, which is lower than when the report was first issued in 2018.

“Just due to breathing the air — something that we all have to do to stay alive — it killed them,” said Qiyam Ansari of the group Valley Clean Air Now. He spoke at an online town hall meeting held Wednesday to discuss the findings in the report.

PM2.5 is a mix of pollutants that includes sulfur dioxide, nitrogen dioxide, ammonia, and hydrogen sulfide.

“Whenever people say PM2.5, think ‘toxic soup’ that’s getting into my lungs,” Ansari said.

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Pollution disproportionately affects certain populations

According to the findings, 80% of the PM2.5 deaths in Allegheny County occurred in people over age 65.

The American Lung Association 2024 State of the Air report also finds that children under age 18, people with respiratory diseases such as asthma and COPD, and those with lung and cardiovascular diseases are at risk from this pollution.

Mortality rates from this pollution were higher in communities with more people living under the poverty line and where more than 30 percent were people of color. Liberty and North Braddock in the Mon Valley near U.S. Steel’s facilities were among those disproportionately affected.

“Where you live should not determine your life expectancy, your health, your access to clean air, or your ability to start or grow a thriving family,” said activist Ebony Flowers, who is a resident of the Mon Valley. “But that is precisely what is happening right now in our community.”

Where does PM2.5 come from, and what’s being done?

Around the country, PM2.5 pollution can come from different sources, such as wildfires and traffic. In Allegheny County, much of it comes from industrial sources, like U.S. Steel’s Clairton Coke Works.

“So steel, coal, other chemical productions, lots of that’s a highly industrial source of PM2.5. That, in some research, has been shown to potentially carry more toxicity than other types of PM 2.5.” explained Dr. Gillian Goobie of Vancouver, British Columbia, who treats patients with lung disease and who studied air pollution, including PM 2.5 pollution and lung disease, while doing her PhD work at the University of Pittsburgh Graduate School of Public Health.

She advocated on behalf of the American Thoracic Society for new federal PM2.5 standards, which were finalized earlier this year.

Goobie, who was not involved in the report, said the Breathe Project used “fairly well-validated methodology,” and the report seems “fairly accurate.”

The report relied on two widely accepted studies to estimate the mortality calculations, and on detailed health data at the local level and refined estimates of annual PM2.5.

Goobie suggested that the work should go through a peer-reviewed process to verify its validity.

“I do think that it would be very valuable to reproduce this data and have it go through a structured or rigorous peer review,” Goobie said.

The Breathe Project report was commissioned by The Heinz Endowments, which also funds The Allegheny Front.

The Allegheny County Health Department did not respond to a request for a comment.

Read more from our partners, The Allegheny Front.

Julie Grant is senior reporter with The Allegheny Front, covering food and agriculture, pollution, and energy development in Pennsylvania and Ohio. Throughout her career, she has traveled as far as Egypt and India for stories, trawled for mussels in the Allegheny River, and got sick in a small aircraft while viewing a gas well pad explosion in rural Ohio. Julie graduated from Miami University of Ohio and studied land ethics at Kent State University. She can be reached at